Driver support system

ABSTRACT

A driver assistance system for a motor vehicle includes output means for outputting information to a vehicle driver of the motor vehicle and/or operating means for operation of the driver assistance system by the vehicle driver, and control means for controlling the information output and/or operation. Means for determining a workload state of the vehicle driver are provided; and the control means are embodied for controlling the information output and/or operation as a function of the workload state of the vehicle driver. A driver assistance system has the advantage that operation of the driver assistance system, and information output by the driver assistance system, are adapted to the workload of the vehicle driver, consequently avoiding overload or excessive distraction of the vehicle driver from traffic events, thus contributing to traffic safety.

BACKGROUND INFORMATION

Driver assistance systems, in the form of vehicle navigation systemsthat output driving direction instructions in acoustic and/or opticalform in order to guide a vehicle driver to a destination along apreviously calculated route of travel, are known. Prior input of thedestination by the vehicle driver, via an operator interface of thevehicle navigation system, is necessary for calculation of the route oftravel. Since destination input while driving constitutes a considerabledistraction from traffic events, suppression of operation of the device,in particular destination input, while the vehicle is being driven hasbeen and is being discussed.

In a known development of such vehicle navigation systems, provision ismade for the driving direction instructions to be outputted not at apredetermined distance before a turning point or general decision point(i.e. for example an expressway exit or intersection), but rather at anincreasing distance from the decision point as the vehicle speed rises.The intended result is that a consistent reaction time for following thedriving direction instructions is made available to the vehicle driver,regardless of the vehicle speed.

SUMMARY OF THE INVENTION

A driver assistance system according to the present invention has theadvantage that operation of the driver assistance system and informationoutput by the driver assistance system are adapted to a particularworkload of the vehicle driver, consequently avoiding overload orexcessive distraction of the vehicle driver from traffic events. Theinvention thus contributes to traffic safety.

In an advantageous development of the invention, provision is made forthe driver assistance system to have a profile memory for storing atleast one user profile; and for information output and/or operationadditionally to be controlled as a function of a user profile stored inthe profile memory. Control of information output and/or operation canthus, in addition to the workload correlation, be individualized inuser-specific fashion.

In summary, the invention thus makes possible, in consideration of thecurrent driving situation, the driver's condition, and optionally thedriver profile (i.e. the vehicle driver's workload resulting therefromas a consequence of driving demands), an adaptation of the outputstrategies and information density of driving instructions in terms ofthe situation (e.g. frequency of messages, output medium, manner ofpresentation); a situation-specific adaptation of operating procedures(e.g. by limiting or inhibiting the functionality of interactions);simplified operation, since decisions are made by the system itself; andthus, ultimately, enhanced driving safety because the driver, incritical situations, can concentrate more on the actual driving task andis not distracted.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a block diagram of the portion of a driver information systemthat is important in terms of the invention, using the example of avehicle navigation system.

DETAILED DESCRIPTION

The invention will be explained below taking the example of a vehiclenavigation system as an example of a driver information system. Thisdoes not, however, imply any limitation of the subject matter of theinvention to vehicle navigation systems.

Vehicle navigation system 1 depicted in FIG. 1 encompasses a controlsystem 10 that preferably is implemented in the form of software and isexecuted by a microprocessor.

Connected to the control system is an operating unit 11 that, asindicated in FIG. 1, encompasses operating elements in the form ofbuttons or keypads. As likewise indicated in FIG. 1, however, operatingunit 11 can also, alternatively or in addition to the aforesaidoperating elements, encompass a voice input device known per se. Lastly,operating unit 11, together with an output unit 12 likewise connected tothe control system, can together constitute an operator interface (alsocalled a man-machine interface or MMI), known per se, for the operationof vehicle navigation system 1.

The above-described operating unit 11 or operator interface serves inthe context of the vehicle navigation system, for example, for input ofa destination for subsequent route-of-travel calculation and destinationguidance.

Output unit 12 connected to control system 10 can encompass both adisplay for optical indication of information and, alternatively or inaddition thereto, an acoustic output. In the case of the vehiclenavigation system, driving direction instructions are outputted in thecontext of the actual destination guidance along a calculated route oftravel, for example, acoustically in the form of spoken instructionsand/or in the form of directional arrows as an optical indication. Thedirectional arrows can be displayed, for example, both as plain arrowsor also against the background of a map depiction. In addition, in thecontext of the input of a destination, letters or names of destinationsselectable via the operating elements are, for example, opticallydepicted on the display apparatus in a manner known per se.

Also connected to control system 10 is a sensor suite 13 for sensingvehicle operating data. Sensor suite 13 encompasses, for example,acceleration sensors for sensing longitudinal and transverseaccelerations of the vehicle that occur as a result of acceleration andbraking operations and during cornering. Such acceleration sensors areused in present-day navigation systems to determine a current vehicleposition but also, for example, for accident detection in combinationwith airbag triggering. Sensor suite 13 further senses, for example, acurrent vehicle speed on the basis of a speedometer signal.

But sensor suite 13 also senses, for example, the switch positions of alight switch for high beams, fog lights, and rear fog lights, windshieldwipers, response of the ABS (antilock braking system) in the event ofhard vehicle deceleration, an external temperature, and other data thatare not exhaustively listed here.

The current workload of the vehicle driver is inferred, from the data ofsensor suite 13, in a driver condition detection system that is hereembodied preferably as a software module of control system 10.

In a situation of little vehicle acceleration and a speed on the orderof 80 to 130 km/h, for example, as is typical when driving calmly onexpressways or secondary roads with few curves and little traffic, thedriver condition detection system decides that the vehicle driver'sworkload is low. If greater longitudinal or transverse accelerations arerecorded for the same speed values, this indicates increased traffic ora route with more curves, and consequently a greater driver workload.Similarly, for example, the fact that a rear fog light or the windshieldwipers are switched on suggests an elevated need for concentration onthe part of the vehicle driver, and thus a greater workload on thevehicle driver as a result of the driving task.

According to a preferred development of the invention, the drivercondition detection system takes into account not only the vehicle datasensed by vehicle sensor system 13, but also contextual data taken froma contextual database 15. Contextual database 15 contains, for example,a digital road map such as the one common in navigation systems. On thebasis of contextual database 15 and a current vehicle positionidentified by the position determination function of the vehiclenavigation system, a determination can be made as to whether the vehicleis located, for example, on an expressway or a secondary road, or ispassing through a town. This additional information can preferably betaken into account by driver condition detection system 14 in order toascertain the vehicle driver's workload. For a vehicle speed of 100 km/hand a location on an expressway, for example, driver condition detectionsystem 14 identifies a lesser workload than for the same speed on anarrow or poorly constructed secondary road.

Further guidelines regarding the workload imposed by the driving taskare supplied by the nature of the route of travel. For example, as thevehicle approaches a segment with many curves or a dangerousintersection, the driver will then need to concentrate more oncontrolling the vehicle. From this in combination with the navigationinformation, a prognosis for driver stress can be prepared.

According to a further development of the invention, driver data, suchas a current body temperature or skin surface conductivity as anindication of perspiration, as sensed by a corresponding driver sensorsuite 16, can additionally be taken into account by driver conditiondetection system 14 in order to ascertain the driver's workload.

Lastly, according to a particularly advantageous development of theinvention that can be combined with all the embodiments and developmentsdescribed above, information from a profile database 17 can additionallybe employed to ascertain the current workload of the vehicle driver. Theuser's preferences are stored in the profile data of profile database17. These include, for example, information as to which output forms heor she prefers in particular situations.

Additionally, for example, the situation-related output of routeguidance instructions desired by the driver can be learned by thesystem. For that purpose, it monitors which display forms or voiceguidance modes the user selects in particular situations, for examplearrow display and detailed voice output in poor weather, or a detailedmap depiction and short voice instructions when traffic density is high.It stores this information in the driver profile in profile database 17.With this self-taught experience, the driver assistance system canprovide the vehicle driver with assistance adapted to the situation.

Based on detection of the vehicle driver's current workload on the basisof detection and evaluation of the driving situation with reference tovehicle operating data and optionally contextual data, the driverprofile, and optionally driver data, control system 10 performs thefollowing functions:

-   -   Selection of the situation-specific voice output strategy in        consideration of driver preferences. This encompasses the        frequency of navigation instructions as well as their level of        detail, ranging from simple directional indications (“left        here,” “now right”) to long, detailed procedural instructions        (“In 500 meters, please turn left onto Hildesheimer Strasse. It        is a sharp turn so please reduce speed.”).    -   Selection of the situation-specific visual route guidance        strategy in consideration of driver preferences. This        encompasses the decision as to what is displayed. The system can        thus decide, for example, whether to show an arrow, a map, or a        three-dimensional depiction of the area. It also decides which        particular screen (center console or combi instrument) to use        for display, and which location on it.    -   Adaptation of the visual output information density. An arrow,        for example, can be displayed normally or in perspective. The        same applies to the map, where decisions must additionally be        made regarding map scale and detail. In the interest of clarity,        for example, all roads that are small or are not on the route of        travel can be removed from the map. For a three-dimensional        output, the display can contain every building or only important        orientation points.    -   In some circumstances, selection of output strategies for other        output media, e.g. noise output, haptic outputs (e.g. force        feedback at the steering wheel).    -   Situation-specific adaptation of operating procedures. This        includes inhibiting all interactions that should not currently        be operable for safety reasons. Other interactions are depicted        in simplified fashion by inhibiting or removing operating        elements for unimportant functions.

The manner of operation of the invention will be elucidated once againbelow with reference to a concrete application example.

The driver enters a destination via the operating elements of thenavigation system and drives off. The road is clear and the weathergood. Because the driving task is simple, the driver condition detectionsystem infers a normal workload. Route guidance instructions aretherefore given frequently and in quite detailed fashion, e.g. “In onekilometer, please turn left onto Robert-Bosch-Strasse.” In addition, themap display is detailed and shows even small roads.

After a while the driving situation deteriorates because a heavy rainbegins. The system detects this by way of the selection of a highwindshield-wiper speed. Because the driver must concentrate more on thedriving task, i.e. because the vehicle driver's workload has increased,from now on the driving directions are given in short and pithy fashion,e.g. “One kilometer, left.” This short form decreases the amount ofinformation that is outputted, and thus distracts the driver less fromthe actual driving task. The frequency of the messages also decreases,and the information content on the map display is reduced, for exampleby the removal of all roads not relevant for destination guidance.

Later on the traffic density increases, so that the vehicle driver mustfrequently adjust his speed. From the frequent braking and accelerationactions, the system infers a very high vehicle driver workload. Forsafety reasons, it deactivates all functions of the navigation systemthat are not immediately necessary, including all settings interactions.This prevents the driver from being distracted from driving events bythe performance of inputs.

1-2. (canceled)
 3. A driver assistance system for a motor vehicle,comprising: at least one of: (a) means for outputting information to avehicle driver of the motor vehicle, and (b) means for operation of thedriver assistance system by the vehicle driver; means for determining aworkload state of the vehicle driver; and means for controlling at leastone of (a) the information output and (b) the operation, as a functionof the workload state of the vehicle driver.
 4. The driver assistancesystem according to claim 3, further comprising a profile memory forstoring at least one user profile, and wherein the controlling is afurther function of the user profile stored in the profile memory.